Virtual orthodontic treatment

ABSTRACT

A method for virtual orthodontic treatment is provided in which a virtual set of orthodontic components is associated, in a virtual space, with a first virtual three-dimensional image of teeth, and then by a set of rules which define the effect of the set of components&#39; teeth, the effect of the virtual treatment can be computed. This virtual treatment can be used to predict the results of a real-life orthodontic treatment as to design such a treatment.

FIELD AND BACKGROUND OF THE INVENTION

The present invention is generally in the field of orthodontics.

An orthodontic treatment has the objects of moving and reorienting teethfor both functional or aesthetic purposes. In such a treatment, theorthodont places a variety of orthodontic components on the teethincluding brackets, which are firmly fixed to the teeth, and othercomponents including wires, tensioning springs, etc., which apply forcesand moments on the teeth, through the brackets, thereby causing theteeth to move. A major problem facing the orthodont is to predict thefinal outcome of the orthodontic treatment. Another problem to focus isto define the proper placement of the brackets and to select the properforce-inducing components to best yield the desired outcome. Currently,the design and predicting of orthodontic treatment based mainly on theorthodont's personal “look and feel” and prior experience skills. Thisapproach is not only error prone but also varies from one individual tothe other, which is obviously undesired.

There is accordingly a need in the art to provide the orthodont with atool for visual demonstration, design or predicting of possible outcomeof an orthodontic treatment. Provided by the invention are method andsystem therefor.

GENERAL DESCRIPTION OF THE INVENTION

In the context of the present description and the appended claims, theterm “movement” or “moving” refers to repositioning teeth, reorientatingteeth, or both. The term “orthodontic treatment” refers to a treatmentintended to move at least one tooth; namely, an orthodontic treatmentshould be understood as encompassing a procedure where all or only partof the teeth (e.g. teeth of one jaw, a group of teeth in a section of ajaw, etc.) are moved. Furthermore, the term “orthodontic treatment”refers both to a treatment intended to yield movement to reach a final,close to ideal outcome of the treatment as well as to an interimtreatment yielding an interim position and orientation of the teeth. Inother words the term “orthodontic treatment” mentioned hereinencompasses both a treatment from an initial stage, i.e. before thetreatment began, through to a final stage; a treatment from an initialstage to an interim stage; as well as to a treatment from an interimstage to another interim or final stage.

The term “virtual treatment” (referred to also, occasionally as virtualorthodontic treatment) as used herein means an orthodontic treatment assimulated on a computer. A virtual treatment may use components (i.e.‘component’ in the virtual computer environment) such as brackets,wires, tensioning springs or rubber bands, corresponding to realcomponents as used in a real life orthodontic treatment, but may alsouse components which are not normally used in real-life treatment; andalso components used in real-life treatment but are used in the virtualtreatment in a different manner. Thus, for example, a virtualorthodontic treatment may use wires which are not normally used in areal life orthodontic treatment; may use wires of a cross-section otherthan such used in a real-life orthodontic treatment; may combine wiresand brackets in a manner whereby the brackets are biased towards arotational movement around the axis of the wire which is usually notperformed in a real-life orthodontic treatment; etc. It will thereforebe understood that the result of virtual treatment is not necessarilythe same as the actual real treatment.

In the following, a method and system for virtual treatment isdisclosed. Manual systems may be used by an orthodont to examine variousalternative treatment paradigms and compare them to one another so as tosee which one will yield the best result. For example, the orthodont maycompare a treatment where one or more teeth are extracted to anothertreatment where all teeth are left in tact. In addition, the system andmethod of the invention may allow also the orthodont to select theorthodontic components which he will eventually use in the real-lifetreatment, to predict the course, time and cost of the treatment. Thiswill all be clarified from the disclosure below.

It will also become clear from the following disclosure, the orthodontictreatment may be made to resemble a real-life orthodontic treatment,although not necessarily so, and occasionally, the orthodontic treatmentmay use components or may apply a set of rules which are not directlyapplicable to real-life treatment.

The present invention provides, by one of its aspects, a method forvirtual orthodontic treatment, comprising:

(a) providing a first virtual three-dimensional image indicative of athree-dimensional (3D) model of teeth from at least one jaw, the modelbeing manipulable so as to allow its viewing from a desired direction;

(b) selecting a via set of orthodontic components, and associating thecomponents with the teeth of said first image so as to obtain a secondimage of said 3D model with said components associated therewith;

(c) using a set of rules, including at least one rule, defining theeffect of said set of components on said teeth, computing the manner ofmovement of the teeth as a result of said effect, so as to obtain athird image comprising the teeth model following the virtual treatment.

The set of orthodontic components selected in step (b) includescomponents which are capable of imparting movement between at least twoteeth. For example, the set may include at least two brackets and awire, may include rubber bands or tensioning springs for forcing twoteeth one against the other, etc. Typically, the set of orthodonticcomponents includes for each jaw, typically, but not necessarily, about5 to about 10 brackets in the case of a child's jaw, and between about 5to about 16 in the case of an adult's jaw.

The set of orthodontic components may be represented as an image whichis similar to the image of the real orthodontic component, as seen inreal life. However, orthodontic component may also be represented by anyother graphic representations. For example, the wire may be representedby a straight or curved line; a bracket may be represented by arectangular frame, etc.

In accordance with some embodiments of the invention, the set ofcomponents includes brackets and a wire and the rule dictates thateventually all slots which receive the wire will be aligned with thewire where the latter is arranged as a splined curve indicative of thedesired result of the virtual treatment. In other words, in this casethe wire represents the desired results of alignment of all slotsfollowing the virtual treatment. Thus, by such an embodiment a componentwhich represents a real-life component, i.e. a wire, is used in adifferent manner than in a real-life treatment in that it dictates theresult of the treatment. This embodiment thus illustrates a generalprinciple in some embodiments of the invention that while in a real-lifetreatment components act in combination to apply forces on teeth ad themovement is a result of such applied forces, in a virtual treatment ofthe invention, the components may also dictate the final result.However, this does not exclude a possibility, in accordance with someother embodiments of the invention, where the movement of the teeth isdictated by forces and moments, which in this case are the set of rules,which act on the teeth under influence of the different components.

Thus, as will be appreciated, occasionally, the component and the set ofrules may be associated with one another. Taking the previouslyillustrated embodiment as an example, the component, which is a wiredefining a splined curve, has with it an associated rule dictating thatthe brackets, with the associated teeth, should move, vertically, butpossibly also horizontally, so that all brackets will eventually bepositioned such that their respective slots are on the splined curvedefined by the wire. In addition to the desired final result, the set ofrules may also stipulate the computational algorithm defining the mannerof movement of the teeth to yield said final result.

The set of rules may also allow, for example, the removal of the toothin certain circumstances. For example, in the case, of crowdness, i.e.insufficient space for all teeth to assume an ideal position andorientation (a position and orientation such that the apex of all teethare essentially on one splined curve), an interfering tooth may beremoved. The removal may, by one embodiment, be automatic; by anotherembodiment, the user may decide in such a case which tooth is to beremoved.

As will be explained in greater detail below, the set of rules is notlimited to a specific implementation. Thus, by way of example, the setof rules may be extracted from a static set of rule database, or by wayof another example from a dynamic learning database holding a rule basethat may be adjusted depending upon e.g. various characteristics of theindividual patient that undergoes the treatment.

The purpose of the virtual orthodontic treatment may be to change therelative orientation of the teeth, to change a distance between theteeth, to alter the inter-occlusion of distance between teeth ofopposite jaws, etc.

In accordance with one example, where the teeth are such that they donot fill the entire space in a jaw (namely with an edge of one toothbeing in proximity to a neighboring tooth), the set of rules may alsoallow the addition of a tooth, which may, in the case of a child's jaw,represent a tooth which has not yet grown or, in the case of an adult'sjaw, a crown which may be implanted in a real-life treatment.

Steps (b) and (c) may be repeated a plurality of times until obtaining adesired result of the virtual treatment. In a repeated step (b), acomponent already selected in a previous step may associated with theteeth model in a different manner, e.g. applying it on a differenttooth, orienting it on a tooth in a different manner, etc.; or newcomponents may be selected, e.g. new brackets, new rubber bands, adifferent wire; etc.

The 3D teeth model may be of all teeth in a jaw, may be a model of teethof both jaws, may be a model of part of the teeth of one or both jaws.

The term “associating” as used herein denotes the entire range ofcombining orthodontic components with teeth and to typically (but notnecessarily) in a manner that stimulates combination thereof in reallife treatment. Typical, but not exclusive examples, being: attachingbrackets to teeth at different positions or orientations; fixing a wireinto the brackets wire-receiving slot; sliding the bracket and the wireone with respect to another, changing the angle of the wire-receivingslot within the bracket so as to change the torque or moment between thewire and the bracket; fixing a tensioning spring or band around twoadjacent teeth; etc. The wire chosen within the framework of the virtualtreatment may have various geometries, e.g. straight or spline cured,and various cross-sectional shapes, e.g. circular, oval, rectangular,etc. (usually to track the ideal curvature of the teeth arrangement in ajaw).

In accordance with another aspect of the invention, there is provided amethod for designing orthodontic treatment of teeth from at least onejaw, comprising:

(a) providing a virtual three-dimensional image indicative of athree-dimensional model of the teeth in a manner allowing manipulationof the model for viewing the model from a desired direction;

(b) selecting a virtual set of orthodontic components corresponding tothose intended to be used in said orthodontic treatment and associatingthe components with the teeth of said first image so as to obtain asecond image of said three-dimensional model with said componentsassociated therewith in a manner representing the manner in which saidcomponents and the teeth may be combined in said orthodontic treatment;

(c) using a set of rules, including at least one rule, defining themanner in which said components affect movement of the teeth, so as toobtain a third image comprising the teeth model after movement of theteeth affected by said components;

(d) repeating steps (a) and (c) until a desired third image is obtained,which desired third image represents a desired position and orientationof teeth following the orthodontic treatment;

(e) recording said second image which yields, following step (c), thedesired third image and using it as a basis for designing theorthodontic treatment.

In addition to allowing a design of the treatment, the method inaccordance with the second aspect may also be used to predict the lengthof the treatment as well as its costs.

By a further aspect the present invention provides a system for avirtual or orthodontic treatment, comprising:

(a) storage means capable of storing a first virtual three-dimensionalimage indicative of a three-dimensional model of teeth of at least one,substantially entire jaw;

(b) user interface for enabling selection of a virtual set oforthodontic components;

(c) processor capable of at least:

(c1) manipulating said three-dimensional model to allow its viewing froma desired direction,

(c2) associating said set with the teeth of said first image to obtain athird image of said three-dimensional model with said componentsassociated therewith, and

(c3) applying a set of rules, including at least one rule, determiningeffect of said components on the teeth so as to cause viral movement ofthe teeth as a result of association with said components to obtain athird teeth model; and

(d) display means for displaying the images.

Regardless of the aspect under consideration, the generation of virtualthree-dimensional image may be obtained, e.g by following the techniquedescribed in PCT Publication No. WO 97/03622, the contents of which isincorporated herein by reference.

By a still further aspect the present invention provides an apparatushaving a memory which contains a digital image representing athree-dimensional teeth model following a orthodontic treatment, whichimage was generated by any of the above methods.

By a further aspect there is provided a memory for storing data foraccess by an application program, implementing the steps (b)-(c)according to a method of each of the above aspects; the applicationprogram being executed on a data processing system; the datarepresenting a first virtual three-dimensional image, indicative of thethree-dimensional model of teeth of one jaw. Also provided is a memoryfor storing data representing a second three-dimensional image, obtainedby implementing the above method.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding, the invention will now be described by wayof example only with reference to the annexed drawings in which:

FIG. 1 illumines two components, a bracket and a wire, selectable by theuser in a virtual treatment in accordance with one embodiment of theinvention;

FIG. 2 is a cross-sectional view along line I-I in FIG. 2;

FIG. 3 is the same cross-sectional view as in FIG. 2, after change inthe slot angle;

FIG. 4 illustrates one view of user interface, according to anembodiment of the invention;

FIG. 5A is a block diagram illustrating the manner of defining abrackets for use in the framework of virtual treatment in accordancewith an embodiment of the invention;

FIGS. 5B-5D illustrate the brackets as viewed in various steps of theselection process;

FIG. 6A is a block diagram illustrating the manner of defining a wirefor use within the framework of a virtual treatment in accordance withan embodiment of the invention;

FIG. 6B and FIG. 6C illustrate the manner in which the wire is viewed invarious steps of the process of FIG. 6 a;

FIG. 7 is a block diagram illustrating the manner of attaching thebrackets onto teeth in the virtual treatment, in accordance with anembodiment of the invention;

FIG. 8 is a block diagram illustrating the steps of matching wires tojaws and vertical movement of teeth to a position dictated by the wire;

FIG. 9 is a block diagram illustrating the steps of horizontal movementof teeth in the case of crowdness, i.e. collision between teeth;

FIG. 10A is a block diagram illustrating the steps of matching wires toa jaw, in accordance with another embodiment of the invention, andmovement of teeth as a result of virtual forces exerted by the wire orthe teeth; and

FIGS. 10B and 10C illustrate the manner in which the association betweenthe wire and the teeth is viewed in two steps of the process of FIG.10A.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a method and system for virtual movementof teeth using the framework or a set of rules from which is based inreal life, although not necessarily identical.

In the following, the invention may at times be described with areference made to various physical entities, such as “jaw”, “bracket”,“wire”, “band”, etc. It should, however, be understood that it implies,in most cases, to a representation of these entities that is used in thevirtual treatment. There are some exceptions where reference is made toreal physical objects, which fact may clearly be inferred based on thecontext.

Teeth movement in a virtual computerized 3D environment for the purposeof planning an orthodontic treatment or for any other purpose, is acomplicated task if this is being performed using hitherto knowntechniques. The use of techniques known to the orthodont from a realorthodontic treatment, simplifies this virtual orthodontic treatment.

The virtual treatment may be required at times, to allow the orthodontto determine a potential outcome of orthodontic treatment. For such apurpose, the virtual treatment need not necessarily follow a course tobe followed by the real orthodontic treatment since the focus may beonly on the final outcome, namely on the final position and orientationof the teeth following the treatment. In such a treatment, the orthodontmay utilize orthodontic components and combination between suchcomponents, even such not used in real life orthodontic treatment.Examples are a selection of a wire with a different geometry than thatused in real life or, change id the slot angle within the brackets so asto yield an angular moment on the teeth about the axis of the wire (seeFIG. 3).

If, however, a virtual treatment is intended to simulate the realtreatment for the purpose of treatment design, preferably (but notnecessarily), only orthodontic components which simulate those used inreal life orthodontic treatment, will be used.

In a typical yet not exclusive sequence of operation in treatment, theuser selects brackets and places them at appropriate positions on thesurface of selected teeth, usually all teeth of the jaw. In most casesbrackets are placed on the buckal teeth surface; however, occasionally,in the virtual treatment brackets may alternatively or additionally beplaced on lingual surfaces of the teeth (this may also be followed attimes in real life orthodontic treatment).

At a next step, the user may define the final desired distance betweenthe teeth (the default is usually zero) and then selects an arch-wirefrom a library of such wires. The library may include wires of differentwidths, different cross-sectional shapes, and different geometries.Optionally, it is possible also to change the geometry of the selectedwire, e.g to make it to follow a tortous path in a vertical and/or ahorizontal plane, etc.

Thereafter, the wire may be associated with the teeth model, forexample, by combining them with brackets fitted on the teeth surface orby attaching them first to virtual anchoring molars, and then to virtualbrackets, etc. The effect of the components on each tooth is thereaftercomputed by the system, based on the set of rules to determine theoutcome of the virtual treatment.

If the virtual treatment uses components which simulate real-lifecomponents, once an optimal result of virtual treatment is reached, theparameters, namely the type of components which were used and the mannerthey were combined with one another and with the teeth model, may berecorded and this may then used to generate a prescription for theorthodontic treatment. Such a prescription may specify the type ofcomponents used, the exact position of each component, e.g. the positionof the bracket on each tooth, etc.

The virtual treatment may obviously also provide a tool to estimate thetreatment length and costs.

The invention will now be further illustrated with reference to somespecific, non-limiting embodiments, with reference to the annexeddrawings.

FIGS. 1-3 show examples of a set of components which can be used inaccordance with an embodiment of the invention. In this specificembodiment, the components consist of a bracket 20 and wire 22 fixed ona surface of a tooth 24, of which only a portion thereof represented bya rectangle is seen. The user has freedom of choice of the exactposition of attachment of the bracket 20 on the surface of the tooth 24and also can slide wire 20 in a longitudinal axis within the receivingslot 26 of the bracket, as represented by the bi-directional arrow 28.

The wire and the bracket may be associated with one another in differentrelative orientations. In the example shown in FIGS. 1 and 2, the wire,which in this case has a rectangular cross-section, is received in aslot with walls parallel and normal to the tooth's surface. By someembodiments of the invention it is possible to change the angle of slot26 about its central axis, as represented by arrow 30, in FIG. 2 toyield a state such as that shown in FIG. 3, wherein wire 22′ has adifferent angular orientation, with respect to bracket 20′, therebyapplying a moment onto tooth 24′.

FIG. 4 shows an example of an embodiment of one out of many possiblevariants of a user interface for realizing the initial componentselection steps. The user can select the brackets from a library, ofbrackets, and similarly can select wires, bands etc. from correspondinglibraries. In addition, the user has the ability to determine the typeof forces and their direction which will act on each tooth.

FIG. 5A illustrates the manner of defining a bracket for use insubsequent virtual treatment steps. In this process, the bracket isdefined with respect to a relative; coordinate system to allow itssubsequent association with the wire, thus defining a “SLOT” frame ofreference; (illustrated graphically in FIGS. 5B and 5C) as well as todefine another coordinate system to facilitate attachment of the bracketto the teeth, thus defining the “BOND” reference frame (illustratedgraphically in FIG. 5D).

Although the steps of bracket definition are typically carried once,while creating the bracket library, it may also be repeated prior toeach virtual treatment step while selecting brackets for the treatment.

FIG. 6A illustrates the steps of choosing a wire and defining it suchthat it can be subsequently used in the framework of virtual treatment.A wire is selected, its initial curve is defined (illustratedgraphically in FIG. 6B) and then the wire is placed in a relativecoordinate system (illustrated graphically in FIG. 6C), so as to definea “WIRE” frame of reference, for subsequent use. Obviously, as will beappreciated, the x-y-z coordinate system of the “WIRE” frame ofreference should correspond to the x-y-z coordinate system of the “SLOT”reference frame.

FIG. 7 illustrates the steps of attachment of a bracket onto a tooth. Ateeth model is: acquired, brackets are selected from the library andeach bracket is placed on a tooth using the “BOND” reference frame, suchthat the z axis of the BOND frame of reference is perpendicular to thesurface. Once the bracket is placed at the desired location, it is bothfixed in this location and then the process is repeated a plurality oftimes in accordance with the number of brackets to be placed on theteeth.

FIG. 8 illustrates the steps of matching the wires to the jaws. Thewires are selected from a library, and placed so that their spline curvewill match that of the jaw or their spline curve may at times be editedto amend it in accordance with the particulars' parameters of the jaw ina particular teeth model. In the specific Example shown, the process isfirst performed for the upper jaw and then for the lower jaw, althoughit will be appreciated that this sequence may be altered, e.g. reversed,performed intermittently in the upper and lower jaws, etc.

In this specific embodiment, the orientation and position of the wiredictates the final result, i.e. final alignment of all slots in thebracket. In other words, in this specific embodiment a set of rulesapplied in the treatment includes, at minimum, a requirement forvertical realignment of the slots, and hence of the teeth to which theyare attached, so that all slots will arrive to the wire. The set ofrules also dictate how to accomplish this result. Put differently, as aresult of the virtual treatment, in the orientation which will beaccomplished in the resulting teeth model, the wire will remain at thesame position and the teeth displaced such that the wire snaps into theslots of the bracket. This procedure is illustrated in FIG. 8, where theset of rules is dictated in blocks 81 and 82.

Another set of rules which can be applied in case of collision betweenthe teeth, i.e. in case of crowdness. This is illustrated in FIG. 9where the teeth are moved horizontally by sliding along the wire, toavoid such collision. The manner in which the treatment is performed mayallow also some user intervention. For example, the user can define someteeth which may have to remain stationary, and others which are allowedto move. Alternatively, the system may have a wider degree of freedom,to allow sideways movement of all teeth. As also illustrated in FIG. 9,it is possible in this process to provide the user with an additionaldegree of freedom, which involves changing the position and/ororientation of the bracket on the tooth surface.

FIG. 10 illustrates another embodiment of teeth movement within theframework of a virtual treatment of the invention. As illustrated inFIG. 10A, wires are obtained, positioned in proximity of the jaw(illustrated graphically for the upper jaw in FIG. 10B), its shapeedited so as to attach to the brackets on the teeth (illustratedgraphically in FIG. 10C) and then the forces applied by the wire on theteeth are calculated and the final position of the teeth obtained canthen be stored.

The present invention has been described with a certain degree ofparticularity but it should be understood that various modifications andalterations may be made without departing from the scope or spirit ofthe invention as defined by the following claims:

1-8. (canceled)
 9. A method for virtual orthodontic treatment,comprising: (a) providing a first virtual three-dimensional (3D) imageindicative of 3D model of all teeth of at least one jaw, the model beingmanipulable so as to allow its viewing from a desired direction; (b)selecting a virtual set of orthodontic components, comprising (i)brackets, one for each tooth in said first image, for attachment toteeth of said image, each of said brackets having a slot for engaging awire, and (ii) one or two archwires, one for each jaw of said firstimage; (c) associating the brackets with the teeth of said first imageso to obtain a second image of said virtual 3D model with the bracketsassociated with the teeth of the model, one bracket on each tooth insaid model; (d) using a set of rules, including a rule that requireseach slot to engage the wire, computing the manner of movement of eachtooth with the bracket associated therewith, so as to obtain a thirdimage comprising the teeth model following the virtual treatment; (e)changing at least one bracket or the manner of associating a bracketwith a tooth and repeating steps (c) and (d) one or more times until theteeth model of said third image represents a desired outcome of theorthodontic treatment.
 10. A method according to claim 9, comprisingproviding a user interface and wherein said selecting comprises usingthe user interface for selecting the virtual set of orthodonticcomponents.
 11. A method according to claim 9, wherein said associatingcomprises manually associating the selected brackets with the teeth ofsaid first image.
 12. A method according to claim 9, wherein saidassociating comprises automatically associating the selected bracketswith the teeth of said first image.
 13. A method according to claim 9,wherein said first image is a virtual representation of athree-dimensional (3D) model of the individual's teeth at interimtreatment stage and said third image is a virtual representation of aninterim or a final treatment stage.
 14. A method according to claim 9,wherein the virtual orthodontic components are represented by an imagewhich is similar to the image of a real life component.
 15. A methodaccording to claim 9, wherein the virtual orthodontic components arerepresented graphically in a manner not resembling the image of a reallife component.
 16. A method according to claim 9, wherein said set ofrules is extracted from a dynamic learning database holding anadjustable rule base.
 17. A method according to claim 16, wherein theadjustment of the database is based on characteristics of the individualundergoing the orthodontic treatment.
 18. A method according to claim 9,comprising virtually extracting one or more teeth from the teeth modelof said first image.
 19. A method according to claim 18, wherein saidset of rules includes a rule that defines movement of teeth to occupyspace previously occupied by an extracted tooth.
 20. A method accordingto claim 18, wherein the virtually extracting is performed manually by auser.
 21. A method according to claim 18, wherein the virtuallyextracting is performed automatically in case of teeth crowdness.
 22. Amethod according to claim 9, comprising virtually adding a tooth to themodel of said first image.
 23. A method according to claim 22, whereinthe added tooth represents one that has not yet grown.
 24. A methodaccording to claim 22, wherein the added tooth represents a crown thatmay be added or implanted in a real-life treatment.
 25. A methodaccording to claim 9, wherein in at least one of said repetitions ofsteps (c) and (d), a position and/or orientation of at least one saidorthodontic components with respect to the tooth it is associated withis changed with respect to a position and/or orientation, respectively,previously held.
 26. A method according to claim 9, wherein in at leastone of said repetitions of steps (c) and (d), the type of orthodonticcomponent associated with at least one tooth is changed with respect tothe orthodontic component previously associated with said tooth.
 27. Amethod according to claim 26, wherein in at least one of saidrepetitions of steps (c) and (d), a position and/or orientation of atleast one said orthodontic components with respect to the tooth it isassociated with is changed with respect to a position and/ororientation, respectively, previously held.